The World Needs Masks. China Makes Them — But Has Been Hoarding Them.

SHANGHAI — As hospitals and governments hunt desperately for respirators and surgical masks to protect doctors and nurses from the coronavirus pandemic, they face a difficult reality: The world depends on China to make them, and the country is only beginning to share.

China made half the world’s masks before the coronavirus emerged there, and it has expanded production nearly 12-fold since then. But it has claimed mask factory output for itself. Purchases and donations also brought China a big chunk of the world’s supply from elsewhere.

Now, worries about mask supplies are rising. As the virus’s global spread escalates, governments around the world are restricting exports of protective gear, which experts say could worsen the pandemic.

That has put growing pressure on China to meet the world’s needs, even as it continues to grapple with the coronavirus itself. Although government data suggests China has brought infection rates under control, epidemiologists warn that its outbreak could flare again as officials loosen travel limits and more people return to work.

Peter Navarro, an adviser to President Trump on manufacturing and trade, contended on Fox Business last month that China had essentially taken over factories that make masks on behalf of American companies. Beijing, he said, had opted to “nationalize effectively 3M, our company.”

In a statement, Minnesota-based 3M said most of the masks it made at its factory in Shanghai had been sold within China even before the outbreak. It declined to comment on when exports from China might resume.

China may be easing its grip as the world’s needs grow. Tan Qunhong, the general manager of a small manufacturer of disposable masks in central China, said that she had filled the government’s purchase orders and was starting to resume exports. The Chinese government is also shipping masks abroad as part of goodwill packages.

Other manufacturers say the Chinese government is still claiming all the masks that their factories in the country make. “Mask exports are still not authorized, but we are following the situation every day,” said Guillaume Laverdure, chief operating officer of Medicom, a Canadian manufacturer that makes three million masks a day at its Shanghai factory.

Much as it dominates manufacturing of cars, steel, electronics and other necessities, China is essential to the world’s supply of protective medical gear. Most of what it makes are the disposable surgical masks worn by health professionals. It makes a smaller number of N95 respirator masks, which provide more filtration for doctors and nurses.

The general public does not need to wear masks, according to the U.S. Centers for Disease Control and Prevention. But demand for surgical masks has skyrocketed in China, where the police require anyone who goes out in public to wear a mask.

Though companies say China is claiming virtually all mask output, the Chinese government said it had never issued a regulation prohibiting mask exports and was willing to work with other countries to share.

“We fully understand the stress and problems that relevant countries are facing at this moment regarding the epidemic, and we are willing to strengthen international cooperation,” said Li Xingqian, the vice director of international trade at China’s Commerce Ministry, in a written reply to questions.

China did not just stop selling masks — it also bought up much of the rest of the world’s supply. According to official data, China imported 56 million respirators and masks in the first week after the January lockdown of the city of Wuhan, where the coronavirus emerged.

On Jan. 30, the last day for which data is available, China managed to import 20 million respirators and surgical masks in just 24 hours. Through February, civic-minded entrepreneurs and aid groups visited pharmacies in affluent countries and emerging markets alike, buying masks in bulk to send to China.

Global companies and charities donated, too. Honeywell provided 500,000 N95 respirator masks, and 3M donated a million of them. Honeywell said its contribution came from stockpiles in China, while 3M declined to identify the source of its donations.

3M also donated a second shipment of respirators, but declined to say how many that included. The charitable foundation of Bristol Myers Squibb funded an additional 220,000 N95 respirators for doctors and nurses at the center of the outbreak.

Since then, China has undertaken a mobilization of wartime proportions to expand its output of disposable surgical masks. Daily production soared from about 10 million at the start of February to 115 million at the end of the month, according to the Chinese government.

Yuan Fajun, the secretary general of the medical materials committee at the China Medical Pharmaceutical Material Association, said manufacturers still needed to produce another 230 million surgical masks for the domestic market. But the recent surge in production means that those orders can be met and exports should be possible, he said.

Hundreds of small companies have started making masks. A General Motors joint venture in southwestern China built 20 of its own mask-making machines and began bulk production.

Yet production of N95 respirator masks has barely increased, to 1.66 million per day. They require a special fabric that is in short supply.

China’s immediate needs may be easing. As new cases soar from Milan to Seattle, Wuhan is reporting fewer than a dozen new infections a day.

The Chinese government has begun some shipments to other countries as part of aid packages. It donated 250,000 masks last month to Iran, one of the countries hardest hit by the epidemic, and 200,000 to the Philippines. This week it said it would send five million masks to South Korea and export 100,000 respirators and two million surgical masks to Italy.

“In the previous stage of prevention and control, many countries have offered to help us, and we are willing to offer affected countries our share of help while we can,” said Mr. Li at the Ministry of Commerce in Beijing.

Analysts in the West say China is also looking for political influence by having top diplomats announce the donations. “It is certainly making it a tool of foreign policy,” said Jacques deLisle, the director of the Center for the Study of Contemporary China at the University of Pennsylvania.

China’s government is not the only one that has played a big role in mask allocation. Taiwan, South Korea and India have all taken steps to stop mask exports.

Citing shortages that endanger doctors and nurses, the French government last week requisitioned all mask production through the end of May. It is also pressing French medical supply factories to produce N95 masks and surgical masks around the clock for domestic use only.

Valmy SAS, a midsize medical supplies maker near Lyon, France, was unable to fulfill an order for a million masks by the British National Health Service because the French government requisitioned supplies. “They tell me what to make and I make it,” said Nicolas Brillat, the company’s director.

The governments did not give production numbers or say how many masks they needed to cover at-risk populations. But officials in Belgium, the Netherlands, Austria and other European Union countries warned that the curbs were preventing suppliers from delivering to neighboring countries.

The bans “risk undermining our collective approach to handle this crisis,” Janez Lenarcic, the E.U.’s crisis management commissioner, said on Friday at an emergency meeting of European health ministers in Brussels.

Supplies from a five-story building in southwestern Shanghai could help alleviate the shortage. The huge factory is one of the most important sites manufacturing N95 respirators for 3M.

Standing at the factory fence, which was topped with six strands of electrified wire, a worker who gave only his family name, Zhou, said the masks had been helping China fight the virus.